Classifications

• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
  • C07C29/00—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom not belonging to a six-membered aromatic ring
  • C07C29/17—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom not belonging to a six-membered aromatic ring by hydrogenation of carbon-to-carbon double or triple bonds

Definitions

• the present invention relates to a process for producing 5-arylpentanols that are useful as synthetic intermediates of perfume, medicaments, agricultural chemicals and the like from pyran compounds.
• An object of the present invention is to provide a process for producing a 5-arylpentanol in a high yield with little amount of by-products.
• Another object of the invention is to provide a process for producing a 5-arylpentanol which does not bring about a problem with regard to corrosion of process equipment and is industrially satisfactory.
• the present inventors have found, after intensive researches, that the aimed product can be obtained in a high yield and industrially satisfactorily while suppressing production of by-products without using a special corrosion-resistant equipment by effecting hydrogenolysis in the presence of a supported catalyst of two or more elements selected from the noble metals in Group VIII in the periodic table and/or an acidic-type palladium-supporting catalyst, and have completed the invention.
• R 1 is preferably an aryl group having in total 6 to 12 carbon atoms which may be substituted with one or two or more of alkyl or alkoxy groups each having 1 to 6 carbon atoms.
• the aryl group includes phenyl group and naphthyl group, and is preferably phenyl group.
• R 1 is particularly preferably phenyl, or o-, m- or p-tolyl, and most preferably phenyl.
• R 2 is preferably a hydrogen atom or an alkyl or alkylidene group having 1 to 6 carbon atoms, more preferably a hydrogen atom, methyl group or methylene group, and most preferably a hydrogen atom or methyl group.
• R 3 is preferably a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, and particularly preferably a hydrogen atom or methyl group.
• Examples of the pyran compounds include 6-phenyl-4-methyl-5,6-dihydro-2H-pyran, 6-phenyl-2,4-dimethyl-5,6-dihydro-2H-pyran, 6-p-tolyl-4-methyl-5,6-dihydro-2H-pyran, 2-phenyl-4-methylenetetrahydro-2H-pyran, and 2-phenyl-4-methyl-5,6-dihydro-2H-pyran.
• One of the preferred embodiments of the present invention is a process for producing a 5-arylpentanol of formula (2a): wherein,
• R 1 and R 3 are the same as those described for R 1 and R 3 in formula (1).
• R 2a is preferably a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, and more preferably a hydrogen atom or methyl group.
• the noble metals include palladium, platinum, rhodium and ruthenium.
• Carriers for the noble metals include carbon, alumina, silica gel, barium sulfate, zeolite and calcium carbonate.
• the catalyst may be two or more noble metals supported on one kind of carrier, or a mixture of two or more kinds of carriers each carrying one kind of noble metal.
• the amount of each noble metal supported on a carrier is preferably 0.1 to 10% by weight, and more preferably 0.2 to 8% by weight of the catalyst.
• Total amount of two or more noble metals supported on carrier(s) is preferably 1 to 20% by weight, more preferably 2 to 10% by weight of the catalyst.
• catalysts can be obtained by a well known method, for example by an impregnation supporting method ( "Catalyst Preparation Chemistry” edited by Atsumu Ozaki, published by Kodansha) in which a carrier is impregnated with a metal and the resulting carrier is reduced with hydrogen at a higher temperature.
• an impregnation supporting method "Catalyst Preparation Chemistry” edited by Atsumu Ozaki, published by Kodansha) in which a carrier is impregnated with a metal and the resulting carrier is reduced with hydrogen at a higher temperature.
• commercial products may be used as they are. Examples of such commercial products include Palladium-Platinum-Carbon powder, Palladium-Carbon Powder, Platinum-Carbon Powder, and Ruthenium-Carbon Powder each manufactured by N. E. Chemcat Corporation.
• the acid type palladium-supporting catalyst used in the present invention means such a solid palladium catalyst in which palladium is supported on at least one carrier selected from alumina, silica gel, barium sulfate, zeolite and calcium carbonate and which shows a pH of less than 7, preferably 2 to 6, particularly preferably 3 to 5.5 when it is dispersed in water.
• a carrier selected from alumina, silica gel, barium sulfate, zeolite and calcium carbonate
• the resulting water has a pH of less than 7, preferably 2 to 6, particularly preferably 3 to 5.5. If the pH of the catalyst is not less than 7, production rate of a 5-arylpentanol significantly decreases.
• the amount of palladium in the catalyst is preferably 0.5 to 10% by weight, particularly 2 to 10% by weight of the catalyst.
• Such catalysts can be obtained by a well known method, for example by impregnating a carrier with a metal according to an impregnation supporting method ( "Catalyst Preparation Chemistry” edited by Atsumu Ozaki, published by Kodansha), and reducing the resulting carrier with hydrogen at a higher temperature.
• commercially available catalysts may be used.
• those having a pH in the above-mentioned range may be used.
• the amount of the catalyst to be used in the invention is usually in a range of 0.01 to 5% by weight, preferably in a range of 0.05 to 5% by weight based on the pyran compounds although it varies depending on the amount of the metals contained in the catalyst; use of too little amount of the catalyst results in a low reaction rate while use of too much amount of the catalyst results in much production of by-products such as hydrocarbons and excessive reaction products wherein the benzene ring of a 5-aryl pentanol is hydrogenated and thus is not economical.
• the catalyst carrying two or more elements selected from the noble metals in Group VIII in the periodic table is used, it is used in an amount of 0.01 to 2% by weight, preferably 0.05 to 1% by weight based on the pyran compounds. Either of the two kinds of the catalysts can be re-used.
• the reaction in the present invention may be carried out using a solvent.
• Alcohol solvents are preferred as the solvent and examples thereof include methanol, ethanol, 1-propanol and 2-propanl. These solvents may be used alone or as a mixture of two or more thereof.
• the amount of the solvent used in the reaction is preferably not more than 60% by weight based on the pyran compound. Alternatively, solvents may not be used.
• the reaction may be conducted at a constant temperature. However, it is preferable to conduct the reaction at a relatively lower temperature in the early stage of reaction and then increase the temperature at the later stage of reaction in order to suppress production of by-products and to increase the production rate of 5-arylpentanols.
• the later stage of reaction begins preferably from the time when conversion of the raw material, pyran compounds, reaches about 60 to 95%, particularly about 80 to 90%, which time usually corresponds to about 1 to 4 hours after commencement of the reaction although such time varies depending on the reaction temperature and the like.
• the reaction temperature in the later stage of reaction is preferably higher than that in the early stage of reaction.
• the temperature is increased with time at a rate preferably in a range of from 3 to 20°C per minute.
• Hydrogenolysis of the pyran compounds is effected at about 30 to 300°C, preferably at about 40 to 200°C.
• the reaction is desirably conducted at about 40 to 100°C, preferably 50 to 80 °C at the early stage of reaction. Thereafter, in the later stage of reaction, the reaction temperature is increased to a temperature higher than that in the early stage of reaction by about 30 to 260°C to enhance the production rate of 5-arylpentanols.
• the temperature in the later stage of reaction is preferably in a range of from about 120 to 180°C.
• Hydrogen pressure during reaction is in a range of 0.2 to 10MPaG, preferably 0.5 to 5MPaG; too lower hydrogen pressure results in insufficient production rate of 5-arylpentanols.
• reaction mixture was filtered to remove the catalyst and was analyzed by gas chromatography. As the result, the yield of 5-phenyl-3-methylpentanol was 93.4%.
• the reaction product contained 1.3% of hydrocarbons and 2.1% of excessive reaction products.
• reaction temperature was raised to 150°C in 19 minutes and reaction was conducted for additional 5 hours.
• reaction mixture was filtered to remove the catalyst and was analyzed by gas chromatography. As the result, the yield of 5-phenyl-3-methylpentanol was 93.0%.
• the reaction product contained 1.8% of hydrocarbons and 2.1% of excessive reaction products.
• reaction mixture was filtered to remove the catalyst and was analyzed by gas chromatography. As the result, the yield of 5-phenyl-3-methylpentanol was 92.0%.
• the reaction product contained 1.9% of hydrocarbons and 4.1% of excessive reaction products.
• reaction mixture was filtered to remove the catalyst and was analyzed by gas chromatography. As the result, the yield of 5-phenyl-3-methylpentanol was 93.1%.
• the reaction product contained 0.8% of hydrocarbons and 3.8% of excessive reaction products.
• 5-arylpentanol can be prepared in a high yield while suppressing production of hydrocarbons and without causing a problem with regard to corrosion of process equipment.

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• 2002
  • 2002-06-11 JP JP2002169630A patent/JP3881288B2/ja not_active Expired - Fee Related
  • 2002-09-25 EP EP20020021724 patent/EP1298118B1/de not_active Expired - Lifetime
  • 2002-09-25 ES ES02021724T patent/ES2296860T3/es not_active Expired - Lifetime
  • 2002-09-25 DE DE2002624968 patent/DE60224968T2/de not_active Expired - Lifetime
  • 2002-09-26 US US10/254,661 patent/US6600079B2/en not_active Expired - Lifetime

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